Mechanical hammer



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Oct. 15, 1935.

F. B. MILLER MECHANICAL HAMMER\ Filed May 16, 1935 2 Sheets-Sheet 2 y" @Q1/fam' QEEDEE/CK B. M/LEE /7/5 #fo/ways.

Patented Oct. 15, 1935 2 UNETED STATES PATENT OFFICE DIECHANICAL HAMMER Frederick B. Miller, Connellsville, Pa.

Application May 16, 1935, Serial No. '21,879

3 Claims.

5 hammers, or picking bars, employs a housing, a

resiliently mounted tool, such as a chisel, and a resiliently mounted helve which is driven through a cam to deliver rapid impacts, or impulses, to the tool. Considerable diiculty has been experienced in using devices of this type, due to the fact that the velocity of the helve, imparted by the cam, controls its limit, or throw. The cam must be constantly rotated at a uniform speed, otherwise the throw of the helve will not be uniform and will result in the striking of the tool shank when it is in its forward position. This necessary uniform speed oi cam rotation is extremely diicult to maintain.

It is one of the objects of the present invention to provide a mechanical hammer employing a helve whose throw is limited independently -of the speed of rotation of the cam by which it is operated.

Another object is to provide a novel mechanical hammer employing a system of springs which operate to absorb unspent forces of the helve, thus assisting its return, and the consequent release from the helvef spring of that amount of pressure, or energy, which is absorbed therein. This manner of operation conserves energy required for the reciprocation of the helve by its operating cam.

In accordance with the teaching of the present invention, the impetus lent the helve is augmented to create a throw which is greater than that of the cam, the length of which is dependent upon the speed of rotation of the latter.

Another object is to provide a novel device of the class described which may be easily and cheaply manufactured, and one which at the same time will prove very durable in service.

These and further objects will be apparent after referring to the accompanying drawings, in which:

Figure 1 is an elevation of the device of the invention shown partly in section.

Figure 2 is a view similar to Figure 1 but disclosing the various elements in another stage of operation.

Figure 3 is an enlarged fragmentary sectional elevation of a part of the device of the invention in the position indicated in Figure 1.

Figure 4 is al sectional view on the line IV--IV in Figure 3.

`Figure 5 is a view ,similar to Figure 2 but `dis\ closing the various elements in another stage of operation.

Figure 6 is a modification. Referring more particularly to the drawing the numeral 2 designates a substantially cylin- .f5 drical housing for the various elements of the device of the invention which is provided on one of its ends with a reduced portion 3, while on the other end thereof `is disposed the usual yoke 4, and handle 5, for enabling its easy handling 10 by a workman.

The housing 2 is Aprovided on its interior surface relatively adjacent its end having the reduced portion 3 with an inwardly extending flange 6, which is centrally apertured, as at 8. 15 This inwardly -extending flange 6 provides within the housing 2 a relatively short cylindrical chamber 9, which is partially closed on its end nearest the reduced portion 3 by an inwardly extending flange I0. Between the flange I Il an-d the re- 20 duced end 3 of the housing 2, the latter is provided with -a relatively narrow annular groove I2, which terminates -in a shoulder I3. A recess I4 of relatively small diameter opens on this shoulder I3 and terminates in a flange I5, 25 which is centrally apertured, as at I6.

The tool shaft of the novel mechanical hammer of the invention is generally indicated as at I8, and is slidably mounted in the apertures 8 and I6 of the flanges 6 and I5, respectively. The 30 extremity of the tool shaft I8 which protrudes from the housing 2 is provided with the usual cutting edge I9, orother medium, for promoting its effectiveness upon that which it is intended to operate. The substantial mid-portion of the 35 tool shaft I8 isprovided with an annular ange 28, and an adjoining retainer flange 2| of greater diameter. A coil spring 23 is disposed in the chamber!) around the tool shaft I8 and in contact with the retainer ange 2l on the latter and 40 the flange 6 o-f the housing 2.

The annular `flange 20 serves to maintain the coil spring 23 against lateral movement on the tool shaft I8. A ange 24 lis provided on the tool shaft vI8 adjacentthe retainer flange 2| and 45 on the side o f the latter which is opposite the annular flange 20. This ange 24 is of substantially the same diameter as that of the opening provided by the inwardly extending flange I0 of the housing 2. A coil spring 25 is disposed in 50 the annular groove I2 and adapted to make contact on one of its ends with the adjacent side of the flange 24 and on its other end with the shoulder I3 on which the recess I4 opens.

The tool shaft I8 is provided on its end adja- 55 spring 46 in the sleeve 3|.

' 49 of the shaft 4|.

A sleeve 3| is disposed for slidable movement` in the elongated cylinder 30 in the housing 2. This sleeve 3| is provided on its end which is most adjacent the flange 21 with an inwardly extending annular flange 33. The other end of the sleeve 3| is closed, as at 34, and carries a frame 35 which has a substantial lateral opening 36 therein. A pair of bearing shoes 31 are disposed on diametrically opposite sides of the opening 36 in the frame 35 in the plane ofthe axis of the sleeve 3|. A reciprocable shaft 38 is disposed to extend through the opening 36 in the frame 35 and carries an eccentrically mounted disk 39 which is adapted to constantly make contact with the shoes 31.

The shaft 38 is driven at a relatively high speed in any suitable manner in accordance with the teaching of the prior art.

A shaft 4| is slidably mounted in the aperture formed by the inwardly extending flange 33 on the sleeve 3| and is provided on its substantial mid-portion with an annular flange 42 and an adjacent relatively elongated cylindrical boss 43 of slightly smaller diameter. The shaft 4| is also provided with a flange 44 on the side of the elongated cylinder 43 which is opposite the flange 42. This shaft 4| in the sleeve 3| vcarries a coil spring 45 which makes contact on one of its ends with the adjacent side of the inwardly extending flange 33, while the other end thereof contacts the adjacent side of the elongated cylindrical boss 43. The annular flange 44 thus serves to center the coil spring 45.

A coil spring 46 is carried by the shaft 4| on the opposite side of the elongated cylindrical boss 43 and is centered by an `annular flange 41 on the latter and a guide plug 48 on the adjacent side of the frame 35.

'Ihe end of the shaft 4| in the sleeve which is adjacent the inwardly extending flange 6 of the housing 2 is reduced in diameter as shown at 49, and made to extend into the cylindrical chamber 29. This reduced portion 49 of the shaft 4| provides a shoulder 5D. A coil spring 5| is disposed in the cylindrical chamber 28 and maintained by means of a retaining washer 52 which contacts the adjacent side of the inwardly extending annular flange 21. In operation, the shaft 38 is constantly rotated with its eccentrically mounted disk 39 in contact with the shoes 31 in the frame v35, thus imparting reciprocation to the elongated sleeve 3|. The shaft 4| is initially moved forwardly through the This movement is, however, resisted by the spring 45 in the elongated sleeve 3| and also the spring 5| in the cylindrical chamber 28, which is compressed by the shoulder 59 formed by the reduced portion It is the function of the spring 23 in the housing 2 to absorb the initial thrust of the shaft |8 caused by maintaining the chisel |9 against the material to be worked upon. The shaft |8 is struck by the shaft 4| and moved forwardly with it, being assisted by the spring 23. the shaft I8 to compress the spring 23 sufficiently to maintain the former in its extreme rearward position, or within the striking range of the shaft 4|. The shoulder 59, formed by the reduced 5 end 49 of the shaft 4|, contacts the retaining washer 52 in the cylindrical chamber 28 and compresses the spring 5|, thereby forming a yielding resistance that limits the throw of the shaft 4| with its elongated cylindrical boss 43 l0 which, taken together, form the helve or ham- 1 mer. The impetus lent the helve by the spring 46 creates a belve-throw greater than the cam-throw, the length of which is dependent on the speed of rotation of the cam. The uni- 15 form throw of the helve is usually dependent upon constant or uniform speed of the cam rotation which is diicult to maintain, due to the usual power fluctuations. Therefore, to keep the movement of the shaft |8 Within certain limits 20 it is desirable to limit the throw of the helve to prevent its being struck at such time when it is in its forward position.

By means of the resistance imparted by the coil spring 5| the throw of the helve is con- 25 trolled without maintaining a constant or uniform speed of cam rotation. Furthermore, the resistance imparted by the coil spring 5I absorbs unspent forces of the helve which assists in returning it, thereby relieving the coil springs 30" 45 and 46 of the amount of pressure or energy absorbed in the former. 'I'his also conserves the energy required for reciprocating the he1ve.

In Figure 6 of the drawings, I have disclosed a modified form of the'device of the invention. 35' According to this embodiment, the main portion of the housing is generally indicated at 65 as comprising a sleeve which carries on one of its ends an extension 61 of reduced diameter. The outer end of the extensio-n 61 is provided with .gy an inwardly extending annular flange 68. A

`washer 69 is disposed between the housing 65 and the extension 61 and serves to retain a ring 10 which is disposed withinthe latter. A similar ring 1| is disposed in the extension 61 against 45 the inwardly extending annular flange 68. 'I'hese rings 69 and 1| are maintained in separated position by a coil spring 12. A shaft 13 extends through the extension 61 and carries a shoulder 14 which is constructed to Contact the ring 1|. 50" This shaft 13 is suitably retained and carries a tool (not shown).

A relatively shorter sleeve 15 is provided in the housing 65 of Figure 6 in lieu of the sleeve 3| in the housing 2 of Figures 1 through 5. This 55. sleeve 15 is provided on its end adjacent the extension 61 with an inwardly extending annular flange 16. The helve of the embodiment of Figure 6 comprises a shaft 19 which has a cylindrical bore in its end adjacent the frame 35. 60 The opposite end of the shaft 19 reciprocates in the aperture provided by the inwardly extending annular flange 16, and is maintained in alinement therewith by an annular flange 8| on its end having the cylindrical bore 8l] which is re- 65 ciprocable within the housing 65.

A coil spring 82 is disposed within the sleeve 15 and around the shaft 19. This coil spring 82 makes contact on one of its ends with the inwardly extending annular flange 16 on the 70' sleeve 15 and on its other end with the annular flange 8| on the shaft 19. A coil spring 83 is disposed to extend into the cylindrical bore 80 in the shaft 19 with its end seating on the bottom thereof. 'I'he other end of the coil spring 'I5 There is not, however, sufficient thrust on A 82 seats against the adjacent side of the frame and is maintained in position by the guide plug 48, all as in the embodiments of Figures 1 through 5.

The mode of operation of the modification of Figure 6 is substantially the same as that previously described. That is to say, the coil spring 'l2 in the extension 61 functions in the same manner as the coil spring 5| in the cylindrical chamber 28, While the springs 82 and 83 function in the same manner as the springs and 46. The remaining elements of both embodiments are identical, the sole purpose of the modification being to reduce the over-all length for operations within confined quarters.

While I have shown and described several specie embodiments of my invention, it will be understood that I do not Wish to be limited exactly thereto, since various modifications may be made without departing from the scope of my invention, as de'ned in the following claims.

I claim:

l. A mechanical hammer comprising a housing, an operating shaft reciprocably mounted in said housing, said shaft being spring-pressed in opposite directions, a helve reciprocably mounted in said housing and in alinement with said operating shaft, said helve being spring-pressed in opposite directions and constructed and arranged to contact the adjacent end of said operating shaft, means for reciprocating said helve, and means in addition to said last named means for controlling the velocity of said helve.

2. A mechanical hammer comprising a housing, an operating shaft reciprocably mounted in said housing, said shaft being spring-pressed in opposite directions, a sleeve reciprocably mounted in said housing, a helve reciprocably mounted in said sleeve and in alinement with said operating shaft, said helve being spring-pressed in opposite directions and constructedand arranged to contact the adjacent end of said operating shaft, means for reciprocating said sleeve, and means in addition to said last named means for controlling the velocity of said helve.

3. A mechanical hammer comprising a housing, an operating shaft reciprocably mounted in said housing, said shaft being spring-pressed in opposite directions, a helve reciprocably mounted in said housing and in alinement With said operating shaft, said helve being spring-pressed in opposite directions and constructed and arranged to contact the adjacent end of said operating shaft, means for reciprocating said helve, and resilient means for controlling the velocity of said helve.

FREDERICK B. MILLER. 

